1. Field of the Invention
The present invention relates to the field of processes for converting oxygenate by-products from the Fischer-Tropsch synthesis to useful hydrocarbon products, particularly, middle distillate.
2. Description of the Prior Art
The conversion of oxygenated organic compounds to hydrocarbons has been the subject of numerous prior-art disclosures. U.S. Pat. No. 3,928,483 discloses a process for the production of aromatic rich gasoline boiling range hydrocarbons from lower alcohols such as methanol, ethanol, propanol and corresponding ethers. In this patent, the process is carried out in two or more stages wherein the alcohol or ether is contacted with a condensation catalyst to produce aliphatic dehydration products and water. The dehydration product is thereafter converted to gasoline boiling hydrocarbon by contact with a special crystalline aluminosilicate zeolite providing a silica-to-alumina ratio greater than 12, a constraint index within the range of 1 to 12 and a dried crystal density of not less than about 1.6 grams per cubic centimeter. A ZSM-5 crystalline zeolite is representative of the special class of zeolite providing the above defining characteristics. U.S. Pat. No. 3,907,915 is directed to the conversion of aliphatic carbonyl containing compounds with the special zeolite above defined. U.S. Pat. No. 3,998,898 is directed to converting a mixture of a difficult to convert aliphatic organic compound in combination with easily converted aliphatic alcohols, esters, acetals and analogs thereof over the special crystalline zeolite above defined to produce highly aromatic gasoline hydrocarbons and light aliphatic hydrocarbons.